The present invention relates to venetian blinds, and more particularly to machines and methods for trimming assembled blinds to desired lengths.
Although venetian blinds are commonly provided in a variety of widths as assembled, the window and doorway openings into which they are installed are not of precisely standard widths. Consequently, there has been a continuous need for supplying blinds custom fitted to the openings into which they will be installed. Rather than fabricate the blinds to custom widths prior to assembly, it has been found desirable to perform trimming as necessary at points of sale, or alternatively at factory locations based on orders received against previously assembled blinds. Accordingly, various devices and machines have been proposed and used in the prior art for this purpose. There are a number of objectives associated with custom trimming, including preserving a symmetrical arrangement of pull-cords, making clean cuts that do not permanently distort either the slats or the upper and lower rails, and enabling relatively unskilled personnel to perform the operation safely, quickly, and accurately. In one class of such machines, one end portion of the assembled blinds is clamped in a collapsed or semi-collapsed condition, one half of the excess length being sheared or sawn from the assembly; then, the assembly is removed from the machine, reversed, and the other end is clamped, the remaining excess length being trimmed in a second operation. See, for example U.S. Pat. No. 5,456,149 to Elsenheimer et al, and U.S. Pat. No. 5,806,394 to Marocco.
It is also known to provide separate cutters for trimming respective ends of the assembly. U.S. Pat. No. 4,819,530 to Huang discloses apparatus including a pair of cutting assemblies that are movably supported for sequentially shearing the slats one at-a-time while in an assembled and opened or tautly spaced-apart condition with the top and bottom rails clamped in place. The cutting assemblies are driven symmetrically in opposite directions according to a desired length of the blinds. Each cutting operation includes advancing the blades to embrace a slat and subsequent displacement of one blade to shear the slat. Separate rail-cutting assemblies for cutting the top and bottom rails. The apparatus of Huang suffers from a number of disadvantages, including excessive complexity and expense of the apparatus, imprecise registration of the cutters relative to the individual slats, and excessively slow operation resulting from the sequential cutting and indexing of the cutters.
U.S. Pat. No. 4,907,325 to Hsu discloses a blind trimmer having a pair of saw-type cutters for cutting respective ends of a blind assembly in a collapsed or clamped-together condition thereof. Each of the cutters is included in a respective cutting mechanism, one of the mechanisms being stationary at one end of the trimmer, the other mechanism being movably mounted in adjustably spaced relation to the first mechanism, each of the mechanisms having associated therewith a clamp for clamping the blinds proximate the finished length thereof, the clamps of each mechanism being movably mounted for advancing the blind assembly for simultaneously trimming the opposite ends. The trimmer of Hsu also exhibits a number of disadvantages, including:
1. The need for movably mounting one cutting mechanism adds undesired complexity and expense;
2. The movable mountings of the clamps are subject to binding when the clamps are activated, in that the direction of movement is perpendicular to the spacing of the clamps;
3. The movable mountings of the clamps are further subject to binding, particularly when the spacing is large, by unsymmetric cutting and driving forces that are likely to be present;
4. The upper and lower rails of the blinds are subject to damage during the cutting operation; and
5. The trimmer is objectionably messy and harmful to operators, producing both chips and scraps that are likely to be scattered and blown about by the rotating saws.
Thus there is a need for a wire termination system that overcomes the disadvantages of the prior art.
The present invention meets this need by providing a dual-end cutting machine having fixed spacing between respective cutting mechanisms. In one aspect of the invention, a machine for trimming assembled blinds having a plurality of slats movably suspended between an upper rail and a lower rail includes a base; a pair of trimming units fixedly supported on the base, each trimming unit having a powered cutting device for cutting components of the blinds in a cutting plane, the cutting planes being parallel-spaced apart by a span distance; a blind-supporting tray carriage supported relative to the base between the cutting planes and guided perpendicular to the cutting planes; and a clamp supported on the tray carriage for fixedly locating the blinds assembly relative thereto in a collapsed condition and oriented perpendicular to the cutting planes, with trimming of respective end portions of the blinds being effected with the blinds clamped to the tray carriage and moved to a desired location relative to respective ones of the cutting planes when the corresponding trimming unit is activated, a finished length of the blinds being the span distance less a distance moved by the carriage between respective trimming operations.
The cutting device of each of the trimming units can include a powered rotary saw that is advancable in its cutting plane relative to the blinds. Each of the trimming units further can also include a saw track supported relative to the base and oriented parallel to the cutting planes, and a saw carriage supported by the track and guided for supporting the saw for movement in its cutting plane. Each of the trimming units can also include an arm pivotally supported on a respective arm axis being oriented perpendicular to the cutting planes, the saw being supported on the arm for arcuate movement in its cutting plane. Preferably each of the trimming units can include the saw track, the saw carriage, the pivotally supported arm, and a handle fixedly projecting from the arm for manually advancing the saw in its cutting plane in a first motion segment wherein the arm pivots about the arm axis, followed by a second motion segment wherein the saw carriage advances parallel to the saw track for facilitating trimming without distortion of components of the assembled blinds.
Preferably the tray carriage is one of a pair of tray carriages, each of the tray carriages supporting a corresponding blinds clamp for clamping the blinds at adjustably spaced-apart locations thereon. The machine can also include a tray carriage track structure fixedly supported on the base and having track surfaces extending a major portion of the span distance between the cutting planes, each of the tray carriages being supported by the carriage track surfaces for translation along the track structure.
Preferably the cutting machine also has a pair of scrap collectors that each include a chip-collection box forming a chip-collecting chamber that extends on opposite sides of a respective one of the cutting planes, the box having a saw opening for admitting a blade of the cutting device, and a workpiece opening for receiving an end portion of the blinds, and an exhaust port for connecting a vacuum device to the chip-collection box for sucking both chips and scraps from the chip-collecting chamber, the exhaust port having an exhaust flow area sufficient for passing the scraps, the exhaust port area being not less than 50 percent of a composite effective inlet area of the chip-collecting chamber when the corresponding trimmer unit is cutting the blinds. Preferably the chip-collection box additionally has a stop opening for receiving an adjustable stop member for registering the blinds prior to cutting, the effective inlet area being inclusive of the effective area of the stop opening. The cutting machine can include the adjustable stop member, the machine also having means for retracting the stop member in response to activation of the associated cutting unit. The cutting machine can include the vacuum device connected to the exhaust duct, the combination of the vacuum device, the chip-collection box, and the duct being effective for exhausting substantially all chips and scraps from the chip-collecting chamber as cutting of the blinds is taking place.
The cutting machine can include a pair of stop mechanisms supported outwardly from the cutting planes for registering the blinds prior to cutting, each stop mechanism including a stop member defining a stop surface parallel to the cutting planes and having a projecting stop arm extending outwardly from and perpendicular to the cutting planes; a stop carriage telescopically receiving the stop arm, the stop carriage being movable between an advanced position and a retracted position in a direction parallel to the stop arm; and means for adjustably clamping the stop arm to the stop carriage to achieve a predetermined distance from the stop surface to the nearest of the cutting planes in the advanced position of the stop carriage. Preferably each of the stop mechanisms also includes a stop actuator for moving the stop carriage to the retracted position in response to activation of a corresponding one of the trimmer units. The stop actuator can include a hydraulic cylinder fixedly supported by the base, with a movable member of the hydraulic cylinder supporting the stop carriage. Preferably a scale rule is mounted relative to one of the stop arm and the stop carriage and a scale reference is mounted relative to the other of the stop arm and the stop carriage for indicating a position of the stop member relative to the stop carriage. Preferably one of the scale rule and the scale reference is adjustably mounted for calibrating readings of the scale rule relative to reductions in length of the blinds to be made by the machine.
In another aspect of the invention, a method for trimming the assembled blinds includes:
(a) providing a machine having first and second trimmer units, each trimmer unit having a cutting plane, the cutting planes being parallel-spaced apart by a span distance, a blinds carriage being movable between and perpendicular to the cutting planes, the cutter units also having respective first and second adjustable stops associated therewith;
(b) clamping the blinds in a collapsed condition to the blinds carriage;
(c) adjusting each of the stops for a desired length of the blinds to be removed from respective ends thereof;
(d) moving the blinds carriage until the rails and slats of the blinds contact the first stop;
(e) activating the first trimmer unit;
(f) advancing the first trimmer unit relative to the carriage for trimming one end of the blinds at the corresponding cutting plane;
(g) moving the carriage until the blinds contact the second stop;
(h) activating the second cutter unit; and
(i) advancing the second cutter unit relative to the carriage for trimming the other end of the blinds at the corresponding cutting plane.
The method can further include retracting the first stop in response to activation of the first trimmer unit, and retracting the second stop in response to activation of the second cutter unit. The method can further include providing for each of the cutter units a chip-collecting chamber that extends on opposite sides of the corresponding cutting plane, the chamber having a blade opening for admitting a blade of the cutting device, a workpiece opening for receiving an end portion of the blinds, and an outlet port; connecting a conduit between each of the outlet ports to a vacuum holding tank; in the moving of the carriage, advancing the blinds into respective ones of the chip collecting chambers; and pumping air from the chambers to the holding tank at sufficient volume and velocity to carry into the tank substantially all chips and scraps being removed by the cutter units.